High optical quality Nd,Y-codoped CaF 2 crystals with diameter 3-inch were obtained by TGT method. Absorption and emission spectra were recorded at 5K, 12K, and 300K respectively. Judd–Ofelt theory was applied to obtain standard parameter Ω t (t=2, 4, 6) and the fitting result of experimental lifetime of Nd 3+ 4 F 3/2 → 4 I 11/2 transition. Broad and flat 1.06μm emission spectra of Nd 3+ ions were obtained with Y 3+ -codoping. The largest emission bandwidth of Nd 3+ 4 F 3/2 → 4 I 11/2 transition is up to 28nm. The results revealed that codoping Y 3+ ions in Nd:CaF 2 crystal can effectively modulate the spectra properties of Nd 3+ ions, in addition to the reduction of fluorescence concentration-quenching.